This application relates generally to gas turbine engines and, more particularly, to gas turbine engine rotor impeller assemblies.
At least some known gas turbine engines include a multi-stage axial compressor, a combustor, and a turbine coupled together in a serial flow arrangement. Airflow entering the compressor is compressed and directed to the combustor where the air is mixed with fuel and ignited, producing hot combustion gases used to drive the turbine. To facilitate cooling components exposed to heat transfer hot combustion gases entering the turbine, at least some known gas turbine engines channel cooling air towards the turbine and associated components.
Compressor bleed air is often used as a source of cooling air for high pressure turbine blades or is used to pressurize a sump. Some known turbine engines include an impeller assembly that enables cooling air to be extracted from a compressor stage at a desired pressure and temperature. However, within known gas turbine engines the rotor impeller assembly is coupled to the rotor at a bolted joint that joins two adjacent stages. More specifically, in such gas turbine engines to facilitate extraction at a desired pressure and temperature, the bleed air is extracted only from a location in the compressor that is generally coincident with the coupling stage joint to enable the impeller assembly to be secured in a portion prior to the adjacent rotor stages being coupled together. Although such a joint enables the two stages to be coupled together, such bolted joints are not located at the desired location to receive bleed air at a desired pressure and temperature. Furthermore, it is difficult to position the rotor impeller assembly because at such bolted joints because of their location, and as such, such impellers may increase the overall assembly time, overall weight, and may facilitate an increase in disk wear.